Mitigation techniques reduce sediment in runoff from furrow-irrigated cropland
California Agriculture 64(3):135-140. DOI: 10.3733/ca.v064n03p135.
Irrigation tailwater can transport sediments and sediment-associated agricultural pollutants to nearby waterways. To help protect the biota of surface waters, we evaluated the use of polyacrylamide (PAM, a synthetic material that flocculates sediments when added to water), vegetated ditches and sediment traps to mitigate sediment losses from furrow-irrigated fields. In a 2-year study, liquid PAM injected into irrigation source water most effectively reduced suspended-sediment concentrations in runoff from different soil types. Dry tablet and granule PAM formulations were also effective, as long as their placement in the furrows promoted their dissolution in irrigation water. Vegetated ditches resulted in intermediate reductions in suspended sediments in tailwater. The sediment traps were limited in their effectiveness by insufficient holding time for fine-grained particulates to settle out of the runoff.
R.F. Long is Farm Advisor, UC Cooperative Extension (UCCE) Yolo County; B.R. Hanson is Cooperative Extension Irrigation and Drainage Specialist, UC Davis; A.E. Fulton is Farm Advisor, UCCE Tehama County; D.P. Weston is Adjunct Professor, UC Berkeley;
We thank the UC Davis Department of Plant Sciences and Department of Land, Air and Water Resources, and the Chico State University Farm for assistance with this study. This project was funded with California Proposition 40 and 50 funds administered by the California State Water Resources Control Board.